Wondering - if you can use the console to add a person to the "wife/husband" faction, couldn't you also use it to remove them and divorce them? If "addfac 19809 1" adds them to the marriage-able faction, so "addfac 19809 -1" would remove them. However I don't know if that would instantly deflag that character as your spouse, but you might want to give it a try. Otherwise there has to be some kind of trait flag someone that indicates them as a spouse that you would be able to remove.